The avoidance of mode locking in laser gyroscopes through the use of mechanically vibrated or individually dithered mirrors in known in the art. Mode locking is the tendency of two counter rotating beams of ring laser radiation to appear to have the same frequency at low levels of angular velocity due to noise or light scattering, thus causing a loss of a desired beat frequency. It is also known in the art to dither or rotate the entire laser gyroscope to prevent mode locking.
For example, in U.S. Pat. No. 4,349,183 there is shown a RLG dither mechanism comprised of a plurality of flexure springs bent by PZT crystals. Each spring has two PZT wafers attached to opposite faces of the spring on a hub side of an axis of inflection and two additional PZT wafers attached to opposite faces on a rim side of the axis of inflection. In U.S. Pat. No. 4,565,941 a RLG dither mechanism is comprised of two wheel shaped flexural elements having PZT material attached to each spoke.
These conventional RLG dither mechanisms can in general be characterized as having a significant degree of mechanical complexity and, therefore, experience those disadvantages inherent in such complexity.
It is thus an object of the invention to provide a reduction in structural complexity, weight and cost in a RLG dither mechanism.
It is a further object of the invention to provide for a RLG dither mechanism that includes piezoelectric material and which achieves high resonant frequencies and a high Q.
It is another object of the invention to provide for a RLG dither mechanism that includes piezoelectric material and which further permits a resonant frequency of the mechanism to be changed without requiring that the mechanical structure also be changed.
It is a still further object of the invention to provide a stiff structure for coupling a laser gyroscope to a mount to minimize compliance of the gyroscope. As used herein compliance is an amount of tilt experienced by the gyroscope rotational axis in response to a horizontal acceleration.